1. Field of the Invention
The present invention relates to a dialog apparatus, a dialog method and a computer program, each configured to inform a user that an application cannot be used in a system, when the application is deleted from the system that can operate a plurality of applications.
2. Description of the Related Art
Systems have hitherto been available, in each of which various applications can be operated. For example, a cellular telephone is a system that can operate a plurality of services (i.e., applications) on a network. Other systems of this type have been developed, such as the car-navigation system into which applications can be downloaded via a cellular telephone. In such a system, the user or the system manager can add new applications and delete some applications, thereby to change the composition of the group of applications.
JP-A 2004-234273 (KOKAI) discloses a method of operating such a system through a natural-language dialog. In this method, the speech-recognition grammar and dialog-promoting procedure are defined for each application. When an application is added or changed, the speech-recognition grammar and new dialog-promoting procedure for the application are added or updated. In this method, as an application is added, the corresponding speech-recognition grammar and new dialog-promoting procedure are added. Thus, when an application is added, an oral dialog can be performed in connection with the application added.
In the method disclosed in JP-A 2004-234273 (KOKAI), the addition and change of applications are indeed defined. However, nothing is defined as to the case where any application becomes not usable (is deleted). Hence, if an application is deleted against the user's intention, the user thinks the application has not been deleted. Consequently, misunderstanding arises on the part of the user, with regard to the existence of the application. For example, the system manager may delete an application that the user can use in the system. In this case, the user thinks that the application can be used, nevertheless. Assume that an access to the application stored in a server is prohibited at the server side. Then, the application cannot be used at all, as if it had been deleted against the user's intention. Even if the user intentionally deletes the application, he or she may forget this fact. Once such misunderstanding has arisen about the application, the user may operate the input device to access the application, though he or she cannot use it at all.
To operate a system in which applications can be deleted, by using a natural language, some measures should be taken against inputs about any application deleted. That is, the inputs about the application must be inhibited. In the conventional system, when an application is added, the dialog-promoting procedure for the application is added. Similarly, when an application is deleted, together with the dialog-promoting procedure for it, dialog-promoting procedures that can respond to an input about the application do not exist at all. Consequently, the system will malfunction if the user operates the input device to access the application that has been deleted. It is therefore necessary to inform the user that the application has been deleted, so that the user may realize that he or she can no longer use the application.
To make the user recognize the deletion of an application, a notice of application deletion may be given the moment the application is deleted. Then, the notice is issued, irrespective of the progress of the dialog with the user. Such a notice often interferes with the dialog with the user. Besides, the notice may fail to make the user recognize the deletion of the application if the application deleted is not so interesting to the user. As a consequence, the user will repeatedly operate the input device in an attempt to access the application that has been deleted. Inevitably, the system will keep malfunctioning.